The IAD dataset starts later than that for DCA and BWI, and starts from April 1, 1960. As with the DCA and BWI data, there appear to be a few days with missing data, as for some years there is only data for 364 days. The actual number of days per year of data was taken into account when computing means. Also, large amounts of data are not available for various dates 1960 through 1963, and of course there is no data for the remainder of 2018. So the plots are from 1964 through 2017.

Each of the graphs can be clicked to be viewed full size.

The first graph is the average daily precipitation. This is total amount of rain per year divided by the number of days in the year. This graph shows a slight increase, from 0.110 to 0.115 inches per day:

Next is a graph of the number of days per year with precipitation, followed by its inverse, the number of days without. The number of days with precipitation has increased from about 114 to 121, or 6 more days. The increases at DCA and BWI were 5 days, and they was over a larger number years. It currently rains about 115 days per year at DCA, and 118 days per year at BWI.

This leads to the next graph, the average rainfall on days when it actually rained. There is no apparent change at all – this graph is flat. So while it rains about 6 more days a year at IAD, the amount of rain, on days when it does rain, is the same. Actually if you squint, it looks like it might be very so slightly decreasing, but it is subtle. And probably going to be different once you add in another year’s worth of data.

Next, we can look at the standard deviation in rainfall amounts on days when it rains, standard deviation is amount of variation of a set of data values around the mean (average). My previous post has a link for more information about standard deviation, as well as the best standard deviation joke for math nerds.

The standard deviation rose from about 0.48 to 0.50, about half the increase seen at BWI. By comparison, the standard deviation was unchanged at DCA. If you torture the data enough, you can find possible reasons for the change. I notice there was a step change / increase in the standard deviation from 2005-2014, which seems to have since stopped. You can also spot a period in the 1990s when the standard deviation was low. I am sure 20 people can find 20 more possible reasons. It’s like a Rorschach test for meteorologists. Here’s the standard deviation plot:

Finally, we can look at the number of days that rained and had rainfall over two standard deviations (using the standard deviation for that year), treating this as significant or extreme rainfall events. The trend of this is completely flat:

To summarize the analysis of rainfall events at DCA, BWI, and IAD:

The number of days with rain is increasing, 5 or 6 more days per year, over the last half century or more, at all three airports.

The average annual measured rainfall is either decreasing (DCA) or increasing (BWI, IAD), depending on which station you look at.

The average amount of rain on days when it does rain is either decreasing (DCA), increasing (BWI) or exactly the same (IAD).

The number of days with significantly high rainfall, exceeding two standard deviations, is either very slightly increasing (BWI) or unchanged (DCA, IAD), depending on which airport you look at.

The BWI dataset starts earlier than tat for DCA, and runs from July 1, 1937 to July 18, 2018. As with the DCA data, there appear to be a few days with missing data, as for some years there is only data for 364 days. The actual number of days per year of data was taken into account when computing means. Also, some data is not plotted for 1945 or 2018, namely the number of days with/without rain for those years, as a full year of data is not available.

Each of the graphs can be clicked to be viewed full size.

The first graph is the average daily precipitation. This is total amount of rain per year divided by the number of days. It shows an increase from roughly 0.108 to 0.121 inches per day from 1939 to 2018. That’s an increase of about 12%.

Next is a graph of the number of days per year with precipitation, followed by its inverse, the number of days without. The number of days with precipitation has increased from about 113 to 118, or 5 more days. This is the same increase we saw at DCA, although it seems rain about 3 fewer days per year at DCA vs BWI (You picked the right airport to leave near, Walter):

That leads to the next graph, the average rainfall on days when it actually rained. This shows an increase from about 0.35 inches to 0.37 inches. (The trend at DCA was actually negative, from 0.37 to 0.35 inches in fact. Exactly opposite. Hmm…):

Next, we can look at the standard deviation in rainfall amounts on days when it rains, standard deviation is amount of variation of a set of data values around the mean (average). My previous post has a link for more information about standard deviation, as well as the best standard deviation joke for math nerds. The standard deviation in rainfall amounts at BWI is increasing. Looking at the graph, the increase seems to be mostly due to an increase during the 2005-2015 period, which has since ended. Is it a short term variation due to random processes, or part of a long term shift?

Next we can look at the number of days that rained and had rainfall over two standard deviations (using the standard deviation for that year), treating this as significant or extreme rainfall events. The trend of this is completely flat:

But, you might ask, isn’t the standard deviation slightly increasing each year? What if we use a fixed standard deviation value, like 0.50 which seems to be the mean value? Doing that, you do see an increase from about 9 to 11 days per year:

Next up… Dulles Airport (which unfortunately has the shortest dataset of all three major airports)

Recently the weather, at least precipitation wise, in the DCA area has been variable. It was very wet and rainy, then we had dry conditions for several weeks with essentially no rain. Now, it is very wet again. Are we seeing extreme (some may say historic) changes in the weather? Or are these just the usual variations?

Are rainfall events are becoming less common, but more extreme? That is, it rains less often, but we get more rain when it does rain, rather than getting rainfall spread out evenly over time as it used to be. And maybe we’re getting more rain overall. Or possibly less rain, those two claims seems to depend on recent weather memory.

To check this claim, data for Washington Reagan National Airport (DCA) was downloaded from the NOAA NCDC site and analyzed in several ways. You can download this data yourself, if you wish: https://www.ncdc.noaa.gov/cdo-web/

The dataset runs from July 1, 1945 to July 18, 2018. There appear to be a few days with missing data, as for some years there is only data for 364 days. The actual number of days per year of data was taken into account when computing means. Also, some data is not plotted for 1945 or 2018, namely the number of days with/without rain for those years, as a full year of data is not available.

Each of the graphs can be clicked to be viewed full size.

First, is there a significant long term trend in the amount of precipitation at DCA? No, there does not seem to be (if you squint you may see a very small decline over time, the sign of this slope likely changes from year to year with normal variability in rainfall):

Second, are rain events becoming less common, but with higher rainfall totals from those events? That would mean we are seeing fewer days with rain, but more rain on those days. The following two graphs show the number of days without any rain, and the number of days with rain, defined as 0.01″ or more. First the number of days without rain. Which is not increasing, but actually decreasing:

And the number of days per year with rain, which of course is just the inverse of the previous graph. It’s raining 5 or 6 more days per year (sorry, Walter):

Third, what about the rainfall totals on days when it actually rains. Is that increasing, leading to more extreme rain events? No, it isn’t. It is actually decreasing, which makes sense considering the mean rainfall per year is essentially steady, and it is raining a few more days out of the year:

OK, maybe it is mostly the same, but we’re getting a few more extreme rainfall events per year? Let’s look at the standard deviation of the rainfall amounts, again only for days when it actually rains.

Standard deviation is amount of variation of a set of data values around the mean (average), there is an explanation here: https://en.wikipedia.org/wiki/Standard_deviation If you get this joke, you understand standard deviation: “Yo mama is so mean she has no standard deviation”

Hmm, no, that is also steady:

One more thing, look at the number of days with very extreme rainfall. How about the number of days where the rainfall exceeded two standard deviations? That also seems to be flat:

Anything else we can check to see if precipitation is indeed getting more extreme in Washington DC? So far, it doesn’t seem to be.

Note, the purpose of this analysis was not to try and discredit man made climate change aka AGW, which is certainly real. Only to see if claims of a noticeable effect on the precipitation patterns in the DC area can be confirmed, which does not seem to be the case.

The privacy of our website visitors is very important to us, and we are committed to safeguarding it. This policy explains what we will do with your personal information.
Consenting to our use of cookies in accordance with the terms of this policy when you first visit our website permits us to use cookies every time you visit our website.
B. Credit
This document was created using a template from SEQ Legal (seqlegal.com)
and modified by Website Planet (www.websiteplanet.com)

C. Collecting personal information

The following types of personal information may be collected, stored, and used:

information about your computer including your IP address, geographical location, browser type and version, and operating system;
information about your visits to and use of this website including the referral source, length of visit, page views, and website navigation paths;
information, such as your email address, that you enter when you register with our website;
information that you enter when you create a profile on our website—for example, your name, profile pictures, gender, birthday, relationship status, interests and hobbies, educational details, and employment details;
information, such as your name and email address, that you enter in order to set up subscriptions to our emails and/or newsletters;
information that you enter while using the services on our website;
information that is generated while using our website, including when, how often, and under what circumstances you use it;
information relating to anything you purchase, services you use, or transactions you make through our website, which includes your name, address, telephone number, email address, and credit card details;
information that you post to our website with the intention of publishing it on the internet, which includes your username, profile pictures, and the content of your posts;
information contained in any communications that you send to us by email or through our website, including its communication content and metadata;
any other personal information that you send to us.
Before you disclose to us the personal information of another person, you must obtain that person’s consent to both the disclosure and the processing of that personal information in accordance with this policy

D. Using your personal information

Personal information submitted to us through our website will be used for the purposes specified in this policy or on the relevant pages of the website. We may use your personal information for the following:

administering our website and business;
personalizing our website for you;
enabling your use of the services available on our website;
sending you goods purchased through our website;
supplying services purchased through our website;
sending statements, invoices, and payment reminders to you, and collecting payments from you;
sending you non-marketing commercial communications;
sending you email notifications that you have specifically requested;
sending you our email newsletter, if you have requested it (you can inform us at any time if you no longer require the newsletter);
sending you marketing communications relating to our business or the businesses of carefully-selected third parties which we think may be of interest to you, by post or, where you have specifically agreed to this, by email or similar technology (you can inform us at any time if you no longer require marketing communications);
providing third parties with statistical information about our users (but those third parties will not be able to identify any individual user from that information);
dealing with inquiries and complaints made by or about you relating to our website;
keeping our website secure and prevent fraud;
verifying compliance with the terms and conditions governing the use of our website (including monitoring private messages sent through our website private messaging service); and
other uses.
If you submit personal information for publication on our website, we will publish and otherwise use that information in accordance with the license you grant to us.

Your privacy settings can be used to limit the publication of your information on our website and can be adjusted using privacy controls on the website.

We will not, without your express consent, supply your personal information to any third party for their or any other third party’s direct marketing.

E. Disclosing personal information

We may disclose your personal information to any of our employees, officers, insurers, professional advisers, agents, suppliers, or subcontractors as reasonably necessary for the purposes set out in this policy.

We may disclose your personal information to any member of our group of companies (this means our subsidiaries, our ultimate holding company and all its subsidiaries) as reasonably necessary for the purposes set out in this policy.

We may disclose your personal information:

to the extent that we are required to do so by law;
in connection with any ongoing or prospective legal proceedings;
in order to establish, exercise, or defend our legal rights (including providing information to others for the purposes of fraud prevention and reducing credit risk);
to the purchaser (or prospective purchaser) of any business or asset that we are (or are contemplating) selling; and
to any person who we reasonably believe may apply to a court or other competent authority for disclosure of that personal information where, in our reasonable opinion, such court or authority would be reasonably likely to order disclosure of that personal information.
Except as provided in this policy, we will not provide your personal information to third parties.

F. International data transfers

Information that we collect may be stored, processed in, and transferred between any of the countries in which we operate in order to enable us to use the information in accordance with this policy.
Information that we collect may be transferred to the following countries which do not have data protection laws equivalent to those in force in the European Economic Area: the United States of America, Russia, Japan, China, and India.
Personal information that you publish on our website or submit for publication on our website may be available, via the internet, around the world. We cannot prevent the use or misuse of such information by others.
You expressly agree to the transfers of personal information described in this Section F.
G. Retaining personal information

This Section G sets out our data retention policies and procedure, which are designed to help ensure that we comply with our legal obligations regarding the retention and deletion of personal information.
Personal information that we process for any purpose or purposes shall not be kept for longer than is necessary for that purpose or those purposes.
Without prejudice to article G-2, we will usually delete personal data falling within the categories set out below at the date/time set out below:
personal data type will be deleted after 24 months.
Notwithstanding the other provisions of this Section G, we will retain documents (including electronic documents) containing personal data:
to the extent that we are required to do so by law;
if we believe that the documents may be relevant to any ongoing or prospective legal proceedings; and
in order to establish, exercise, or defend our legal rights (including providing information to others for the purposes of fraud prevention and reducing credit risk).
H. Security of your personal information

We will take reasonable technical and organizational precautions to prevent the loss, misuse, or alteration of your personal information.
We will store all the personal information you provide on our secure (password- and firewall-protected) servers.
All electronic financial transactions entered into through our website will be protected by encryption technology.
You acknowledge that the transmission of information over the internet is inherently insecure, and we cannot guarantee the security of data sent over the internet.
You are responsible for keeping the password you use for accessing our website confidential; we will not ask you for your password (except when you log in to our website).
I. Amendments

We may update this policy from time to time by publishing a new version on our website. You should check this page occasionally to ensure you understand any changes to this policy. We may notify you of changes to this policy by email or through the private messaging system on our website.

J. Your rights

You may instruct us to provide you with any personal information we hold about you; provision of such information will be subject to the following:

the payment of a fee to be determined based on the cost to provide the data; and
the supply of appropriate evidence of your identity, we will usually accept a photocopy of your passport certified by a notary plus an original copy of a utility bill showing your current address.
We may withhold personal information that you request to the extent permitted by law.

You may instruct us at any time not to process your personal information for marketing purposes.

In practice, you will usually either expressly agree in advance to our use of your personal information for marketing purposes, or we will provide you with an opportunity to opt out of the use of your personal information for marketing purposes.

K. Third party websites

Our website includes hyperlinks to, and details of, third party websites. We have no control over, and are not responsible for, the privacy policies and practices of third parties.

L. Updating information

Please let us know if the personal information that we hold about you needs to be corrected or updated.

M. Cookies

Our website uses cookies. A cookie is a file containing an identifier (a string of letters and numbers) that is sent by a web server to a web browser and is stored by the browser. The identifier is then sent back to the server each time the browser requests a page from the server. Cookies may be either “persistent” cookies or “session” cookies: a persistent cookie will be stored by a web browser and will remain valid until its set expiry date, unless deleted by the user before the expiry date; a session cookie, on the other hand, will expire at the end of the user session, when the web browser is closed. Cookies do not typically contain any information that personally identifies a user, but personal information that we store about you may be linked to the information stored in and obtained from cookies.
We use both session and persistent cookies on our website.

The names of the cookies that we use on our website, and the purposes for which they are used, are set out below:
we use Google Analytics and Adwords on our website to recognize a computer when a user visits the website, track users as they navigate the website, enable the use of a shopping cart on the website,
improve the website’s usability, analyze the use of the website, administer the website, prevent fraud and improve the security of the website, personalize the website for each user,
target advertisements which may be of particular interest to specific users.
Most browsers allow you to refuse to accept cookies—for example:
in Internet Explorer (version 10) you can block cookies using the cookie handling override settings available by clicking “Tools,” “Internet Options,” “Privacy,” and then “Advanced”;
in Firefox (version 24) you can block all cookies by clicking “Tools,” “Options,” “Privacy,” selecting “Use custom settings for history” from the drop-down menu, and unticking “Accept cookies from sites”; and
in Chrome (version 29), you can block all cookies by accessing the “Customize and control” menu, and clicking “Settings,” “Show advanced settings,” and “Content settings,” and then selecting “Block sites from setting any data” under the “Cookies” heading.
Blocking all cookies will have a negative impact upon the usability of many websites. If you block cookies, you will not be able to use all the features on our website.

You can delete cookies already stored on your computer—for example:
in Internet Explorer (version 10), you must manually delete cookie files (you can find instructions for doing so at http://support.microsoft.com/kb/278835 );
in Firefox (version 24), you can delete cookies by clicking “Tools,” “Options,” and “Privacy”, then selecting “Use custom settings for history”, clicking “Show Cookies,” and then clicking “Remove All Cookies”; and
in Chrome (version 29), you can delete all cookies by accessing the “Customize and control” menu, and clicking “Settings,” “Show advanced settings,” and “Clear browsing data,” and then selecting “Delete cookies and other site and plug-in data” before clicking “Clear browsing data.”
Deleting cookies will have a negative impact on the usability of many websites.

Looking for a new DX challenge? In addition to shortwave pirate stations in the USA, and Europe (Europirates as we call them), there’s a relatively new group of pirate radio stations being heard in North America, those from South America.

It’s really only been the previous year that we’ve confirmed that there’s a significant number of pirate radio stations in South America that can be received here. Radio Pirana has been known for some time, and I believe thee were a few reports of it, and at least one other station that I cannot remember the name of, but that’s about it. For years there have been logs of very weak UNID stations heard on the 43 meter band (6800-7000 kHz), presumed to be pirates of some sort, and it is possible some of these were South American pirates.

Most of these stations use homemade transmitters, often of the “Lulu” design, with a IRF510 or similar MOSET RF final stage. That means they are generally in the 15 or 20 watt carrier range, although some are higher power. That also means that unless otherwise noted, all of these stations use AM mode, and in general the frequency is highly variable, easily varying 100 Hz or more from night to night, or even during transmissions.

One important caveat: Since most of these stations use relatively low power, and due to the long distances involved, signal levels are generally weak, although occasionally when conditions are excellent (especially if there’s grayline propagation), they can put in stronger signals. I am fortunate to live in a rural area with relatively low noise/RFI levels, and have several high end receivers and large antennas. My primary setup for catching these stations is a netSDR receiver and a 670 foot Sky Loop antenna. You’re going to want to use the best receiver and antenna you can for catching these stations, you’re not likely to have good (or any) results with a portable SW radio, RTL dongle, or small/indoor antenna. Also, I record the entire 43 meter band nightly on my netSDR, and then go through the recordings each morning. This lets me catch stations that may only appear for a brief period of time. That said, you can still hear them with a reasonable HF setup, although it may take persistence, checking each night, until conditions permit reception.

And for those of you into collecting QSLs – many of these stations are reliable QSLers!

In general, the easiest station to hear is Lupo Radio from Argentina. It is on the air most evenings on 6973 kHz in AM mode. At least at my location, it puts in the strongest and most reliable signal. Usually in the SIO 222 to 333 range, sometimes stronger. There are frequent IDs. I use Lupo Radio as a “beacon” to gauge how good conditions are to South America on 43 meters.

Another station that is often on the air is RCW – Radio Compañía Worldwide from Chile. They use 6925.13 kHz, and their carrier is more stable and usually on this offset frequency, which makes it easier to determine that it’s likely you’re hearing them vs a US pirate station.

Also new to the scene is an as yet UNID pirate from South America on 6934.9 kHz. I have received them for several weeks now in the local evenings, usually starting around the 2300-0300 UTC window. They put in a respectable signal (relatively speaking), strong enough for Shazam to ID songs. They have frequent breaks in their transmission, with the carrier often going off and on many times during a broadcast. They also occasionally transmit audio test tones, and sometimes seem to relay audio from licensed stations in Argentina such as Radio El Mundo. This could be someone testing a new transmitter? A new mystery to solve!

Radio Dontri is somewhat unique in that they use USB mode, on 6955 kHz. They also send SSTV, which is sometimes easier to receive than music, and helps to verify that you’re actually hearing them, vs a US pirate on 6955. They tend to drift a lot, however, which can make decoding the SSTV transmissions challenging.

Outside the 43 meter band, there is Rádio Casa 8000 kHz. I have only received weak carriers from this station, although partly that may be because I do not frequently check for it, and it does not turn up on my overnight SDR recordings.

Radio Triunfal Evangélica is other station outside of the 43 meter band, they use the nominal frequency of 5825 kHz, often closer to 5824.9 kHz. Again I have only received a carrier from them. As the name implies, they are a religious station, affiliated with a church.

Now that we’ve talked about the pirate stations from South America, we should probably mention things you are likely to hear that are not pirates. Specifically, what we call Peskies (or Pesky as the singular), short for pescadores, the Spanish word for fishermen. Peskies generally use LSB mode, and can be heard on many frequencies in the 43 meter band, engaging in QSOs. Years ago, pirate listeners started to call these stations pescadores, since some of them were indeed fishermen, and could be heard discussing related matters. It might be better to think of most of them as freebanders/outbanders, much in the tradition of those transmitting on 11 meters. There’s a logging forum on the HFU dedicated to Peskies, if you’re interesting in learning more about them.

Occasionally they use AM mode. We’ve logged several on 6965 kHz (+/- of course), that at first were thought to be pirates. But they never transmitted music, and after some discussions with DXers in South America, it was determined that they were more properly considered peskies.

Several pirate stations use 1710 kHz, but reception here is difficult, due to the Hudson County NJ TIS station, which puts in a strong signal. It’s an annoying pest, and seems to just play the same 3 or 4 pre-recorded messages over and over. I doubt anyone in Hudson County actually listens to it.

Last night, I started to hear some music on 1710 around 2350 UTC (6 February 2018), so I decided to stick around and listen. I also started the SDR recording. Glad I did!

The station was fading in and out, so my reception was alternating with the TIS.

Here’s what I heard. Some songs were ID’d with Shazam, so they could be iffy, plus there could be another station in there:

I ran the SDR recording files through my Carrier Sleuth app, and produced this high resolution waterfall of 1710 kHz. Click on the image to view it full sized.

The pirate is the carrier around 1710.009 kHz that goes QRT around 0234 UTC. The carrier around 1710.0025 kHz is the Hudson County TIS. I think one of the carriers is another TIS in PA, I heard a mention of an address in PA at one point. Probably KID-761, Bedford, PA, the Flight 93 Memorial.

Look at all the other carriers on 1710! One is probably the Springfield MA TIS, others may be pirates? I am not sure how many other TIS stations are authorized on 1710.

It’s very interesting how there is another carrier around 1709.995 kHz that went QRT the same time as the pirate. It is weaker, and does not have the same wiggles as the pirate carrier, so I do not think it is a locally produced image. I am not sure what it is, or if the sign off time is coincidental.

If the operator of the 1710 pirate sees this post, and would like to send me a QSL / eQSL, it would be greatly appreciated!

I discovered a new QRM / RFI source today, my wife’s new KitchenAid 7-Quart Pro Line Stand Mixer. Here’s a waterfall screenshot after it turned on, you can see the roughly 15 kHz spaced bands of interference. These use a DC motor, presumably that is the cause of the RFI, vs mixers with a regular AC motor.

Fortunately she doesn’t use it that often, and she’s testing out a new low carb dough recipe, so I can live with it. Speaking of low carb, here’s our low carb pizza recipe.